Am currently applying for jobs and have to write alot of application letters - (almost) same content every time, only the date changes. All of these letters are named letter.pdf. As of now, am having to create multiple folders named by date, like 15th, 1st, etc to know which letter is for what date.

My question is, is it possible to have all these letters in the same folder, with the same name but use something like the modified date to differentiate them?